Max Rear Tyre size

[connorleeneil13]

Good Morning,
I Own a 1990 sportster and would like to increase the rear tyre size without chopping the frame, can anyone tell me the maximum tyre size I can stick in the rear end.
I am currently running a 140, I still have plenty of room within the swingarm and I think 150 maybe even a 160 could fit.

[HD1200R]

I think the widest tire you can do on the stock rim is 150. Anything larger can be hazardous due to improper fitment.